How to create this extruded piece from a rectangle?
I would probably start with an "Inset" operation (I) to create the geometry for the center hole, then move it slightly on the Y and Z axis and then eventually remove the face in the middle of the inset. Further detailing steps (such as solidification and bevelling) are of course necessary but that should give you a starting point.

If that's not what you were after, please clarify the question. I'm assuming you want to model the pictured piece in Blender.